Ms. McLane is herself a poet, and a pretty terrific one. In “Late October,” from her most recent collection, 2010’s World Enough, she writes:

From here I see the tone

I adopted was the air

I was breathing

unknowing half knowing

This new gathering of essays traces that adoption of tone, the myriad ways a writer becomes who she is without knowing it, immersed in an atmosphere of influence and inspiration so pervasive it is invisible as the air.

My Poets opens, after four epigraphs, with a “Proem in the Form of a Q&A”—25 interview-type questions (though many are repeated) followed by an apposite quotation from a beloved poem. It sounds fey, but it’s charming:

Why do you read poetry?

Batter my heart.

Why do you read poetry?

I have wasted my life.

The first “response” is Donne’s imperative to “three-person’d God;” the second James Wright’s revision of Rilke while “Lying in a Hammock at William Duffy’s Farm in Pine Island, Minnesota.” In this proem, or preface, Ms. McLane telescopes the method she follows throughout the book: quotations agglutinate until, instead of merely illustrating her thought, they form part of it.

Her offhand implication that poems can be, as the critic Kenneth Burke called them, “equipment for living,” is all the more effective for its refusal of the treacly didactic mode common to poetry primers. In The Poetry Home Repair Manual, Ted Kooser, the 13th U.S. Poet Laureate, wrote, “Poetry’s purpose is to reach other people and to touch their hearts.” Ms. McLane, for whom Marianne Moore is “a stealth weapon” with a “courtly feline bitchiness,” would sooner chew off her own arm than write a sentence like that. As she says, her heart is battered by poetry:

Louise Glück’s Wild Iris was a companion more intimate than any living friend, a murmur and rasp and balm in the mind those months the structures of living you yourself had erected were now collapsing, the foundations battered by you yourself.

She goes on to describe a reading where Glück followed “a jokey comic fellow” and began to read: “all the air went out of the room.” Ms. McLane then offers a succinct, awestruck appreciation of what poetry can do: “To empty a room of its air like that. To annihilate its complacence.” Sounds a little more impressive than “touching hearts.”

Ms. McLane’s discussions of her poets are interwoven with autobiographical accounts of what was going on in her life when she discovered them. When this doesn’t work, it comes across as melodrama. (If the dissolution of a marriage is the worst thing that ever happened to you, you’ve lived a blessed life indeed.) But at other times, she is able to elucidate why poetry can matter to a life without straining for the unconvincing uplift that mars so many books on poetry written for a general audience.

The most illuminating chapter here, “My Impasses,” is also the most self-deprecating. It is subtitled “On Not Being Able to Read Poetry,” a topic anyone who’s breathed poetic airs can relate to. What earnest college student’s Norton anthologies aren’t filled, like Ms. McLane’s, with now-embarrassing marginalia attesting to an excruciating literalism? Ms. McLane reproduces a page from her college textbook on which Frank O’Hara’s “The Day Lady Died” appeared. “Not US,” Harvard undergrad McLane scrawled next to the line about picking up a magazine “to see what the poets / in Ghana are doing these days.” O’Hara’s poem continues:

I go on to the bank

and Miss Stillwagon (first name Linda I once heard)

doesn’t even look up my balance for once in her life.

The bit about the first name is underlined, the words “is not sure” dutifully recorded in the margins. “For once in her life” earns an astute “unexpected.”

Ms. McLane is acidic in her appraisal of her younger self—“I cannot believe what an idiot I was!”—but forgiving, too: “And yet, of course I can.” Reading poetry well is an art, and it must be learned, like any other:

I had yet to share in the relevant communal sense-making procedures (the horizon of expectation, the interpretive community, what have you) that would make this text readable. One must be gentle with one’s former self, one’s students, one’s current muddles, with anyone honestly trying but not getting it.

The perspective from which those awkward, clueless people we used to be seem idiotic is a perspective earned by long training. That there are people as patient as Ms. McLane, who remember what it was like “not to get it,” and who take the time to teach poetry or write about it, is a lucky thing for those who are just now struggling to find their way round Apollo’s western islands.

For that, Ms. McLane is breezy and learned at the same time:

For William Carlos Williams it was no ideas but in things.

I first heard this in 1985, in a freshman poetry class.

I was like, WTF?

A book this ambitious in its range of tones and registers will inevitably break down in parts. Sometimes Ms. McLane’s learning is worn so casually she might as well be naked: while the quotations from poems function as an index of delight, the numbing invocations of Badiou, Wittgenstein, Foucault, Bersani, Elaine Scarry and other grad-seminar fetishes usually add nothing whatsoever to the discussion, and distract from it by participating in the sort of English department puffery you’d think Ms. McLane would disdain. Critical works on poetry should by no means avoid or apologize for intellectual elitism—such elitism is a prerequisite for training in poetic thinking—but the names should do more than sit there on the page like Boy Scout badges. And there are some disheveled musings on Dickinson as a “post-9/11 poet,” in which Ms. McLane indulges the hoariest caricatures of Calvinism and offers the sort of liberal critique of the “war on terror” you’ve read a hundred times before.

But it’s refreshing to read a book about learning to love poetry that risks such misfires. She is clearly having fun, providing a welcome corrective to the notion that studying poetry is a matter of tracking down all the allusions in “The Waste Land” and noting that Langston Hughes opposed racism. She ventriloquizes Gertrude Stein, Christopher Smart, William Wordsworth, turning their stylistic tics into insights. If you already love poetry, Ms. McLane’s book will rekindle old passions and ignite new ones.

And if you don’t already love poetry, well, the central insight of My Poets, as of all literary criticism, is laid out in Ms. McLane’s chapter on “My Shelley / (My Romantics)”: “I had no imagination so I sought out the imaginers.” In her final chapter, she constructs a collage of borrowed lines ranging across millennia:

I’m beginning to know

myself. I don’t exist.

’Tis strange the mind, that very fiery particle!

I, so given to indolence, so easily bored:

I have had to learn the simplest things / last.

The first and third lines are Pessoa (writing as Álvaro de Campos), the second Byron and the last Charles Olson. For Pessoa’s “heteronym” de Campos, “I don’t exist” is of course the simple truth. Pessoa invented biographies and different poetic styles for each of the heteronyms he wrote under. But the line contains, in the context Ms. McLane assembles, a deeper truth as well, about poetry itself and the art of reading it. It is not quite an irony that we only begin to know ourselves, only begin to exist, through our shaping encounters with other minds. Deep reading has historically been privileged among such encounters, and it remains the surest method of cultivation, of what Nietzsche called becoming who one is.

This has to be experienced firsthand: there’s no way to convince a young person who doesn’t read that in order to have an imagination one must first seek out the imaginers, that without them a life is less. You can only place a book in her hands and hope for a spark. This book would do.